| 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 11. The smb.conf file</title><link rel="stylesheet" href="samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.71.0"><link rel="start" href="index.html" title="SAMBA Developers Guide"><link rel="up" href="pt03.html" title="Part III. Samba Subsystems"><link rel="prev" href="vfs.html" title="Chapter 10. VFS Modules"><link rel="next" href="wins.html" title="Chapter 12. Samba WINS Internals"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 11. The smb.conf file</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="vfs.html">Prev</a> </td><th width="60%" align="center">Part III. Samba Subsystems</th><td width="20%" align="right"> <a accesskey="n" href="wins.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="parsing"></a>Chapter 11. The smb.conf file</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Chris</span> <span class="surname">Hertel</span></h3></div></div><div><p class="pubdate">November 1997</p></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="parsing.html#id325526">Lexical Analysis</a></span></dt><dd><dl><dt><span class="sect2"><a href="parsing.html#id325594">Handling of Whitespace</a></span></dt><dt><span class="sect2"><a href="parsing.html#id325635">Handling of Line Continuation</a></span></dt><dt><span class="sect2"><a href="parsing.html#id325680">Line Continuation Quirks</a></span></dt></dl></dd><dt><span class="sect1"><a href="parsing.html#id325754">Syntax</a></span></dt><dd><dl><dt><span class="sect2"><a href="parsing.html#id325806">About params.c</a></span></dt></dl></dd></dl></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id325526"></a>Lexical Analysis</h2></div></div></div><p>
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| 2 | Basically, the file is processed on a line by line basis. There are
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| 3 | four types of lines that are recognized by the lexical analyzer
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| 4 | (params.c):
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| 5 | </p><div class="orderedlist"><ol type="1"><li><p>
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| 6 | Blank lines - Lines containing only whitespace.
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| 7 | </p></li><li><p>
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| 8 | Comment lines - Lines beginning with either a semi-colon or a
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| 9 | pound sign (';' or '#').
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| 10 | </p></li><li><p>
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| 11 | Section header lines - Lines beginning with an open square bracket ('[').
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| 12 | </p></li><li><p>
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| 13 | Parameter lines - Lines beginning with any other character.
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| 14 | (The default line type.)
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| 15 | </p></li></ol></div><p>
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| 16 | The first two are handled exclusively by the lexical analyzer, which
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| 17 | ignores them. The latter two line types are scanned for
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| 18 | </p><div class="orderedlist"><ol type="1"><li><p>
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| 19 | - Section names
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| 20 | </p></li><li><p>
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| 21 | - Parameter names
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| 22 | </p></li><li><p>
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| 23 | - Parameter values
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| 24 | </p></li></ol></div><p>
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| 25 | These are the only tokens passed to the parameter loader
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| 26 | (loadparm.c). Parameter names and values are divided from one
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| 27 | another by an equal sign: '='.
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| 28 | </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id325594"></a>Handling of Whitespace</h3></div></div></div><p>
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| 29 | Whitespace is defined as all characters recognized by the isspace()
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| 30 | function (see ctype(3C)) except for the newline character ('\n')
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| 31 | The newline is excluded because it identifies the end of the line.
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| 32 | </p><div class="orderedlist"><ol type="1"><li><p>
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| 33 | The lexical analyzer scans past white space at the beginning of a line.
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| 34 | </p></li><li><p>
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| 35 | Section and parameter names may contain internal white space. All
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| 36 | whitespace within a name is compressed to a single space character.
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| 37 | </p></li><li><p>
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| 38 | Internal whitespace within a parameter value is kept verbatim with
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| 39 | the exception of carriage return characters ('\r'), all of which
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| 40 | are removed.
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| 41 | </p></li><li><p>
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| 42 | Leading and trailing whitespace is removed from names and values.
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| 43 | </p></li></ol></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id325635"></a>Handling of Line Continuation</h3></div></div></div><p>
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| 44 | Long section header and parameter lines may be extended across
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| 45 | multiple lines by use of the backslash character ('\\'). Line
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| 46 | continuation is ignored for blank and comment lines.
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| 47 | </p><p>
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| 48 | If the last (non-whitespace) character within a section header or on
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| 49 | a parameter line is a backslash, then the next line will be
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| 50 | (logically) concatonated with the current line by the lexical
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| 51 | analyzer. For example:
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| 52 | </p><pre class="programlisting">
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| 53 | param name = parameter value string \
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| 54 | with line continuation.
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| 55 | </pre><p>Would be read as</p><pre class="programlisting">
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| 56 | param name = parameter value string with line continuation.
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| 57 | </pre><p>
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| 58 | Note that there are five spaces following the word 'string',
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| 59 | representing the one space between 'string' and '\\' in the top
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| 60 | line, plus the four preceeding the word 'with' in the second line.
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| 61 | (Yes, I'm counting the indentation.)
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| 62 | </p><p>
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| 63 | Line continuation characters are ignored on blank lines and at the end
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| 64 | of comments. They are *only* recognized within section and parameter
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| 65 | lines.
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| 66 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id325680"></a>Line Continuation Quirks</h3></div></div></div><p>Note the following example:</p><pre class="programlisting">
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| 67 | param name = parameter value string \
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| 68 | \
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| 69 | with line continuation.
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| 70 | </pre><p>
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| 71 | The middle line is *not* parsed as a blank line because it is first
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| 72 | concatonated with the top line. The result is
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| 73 | </p><pre class="programlisting">
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| 74 | param name = parameter value string with line continuation.
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| 75 | </pre><p>The same is true for comment lines.</p><pre class="programlisting">
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| 76 | param name = parameter value string \
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| 77 | ; comment \
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| 78 | with a comment.
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| 79 | </pre><p>This becomes:</p><pre class="programlisting">
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| 80 | param name = parameter value string ; comment with a comment.
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| 81 | </pre><p>
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| 82 | On a section header line, the closing bracket (']') is considered a
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| 83 | terminating character, and the rest of the line is ignored. The lines
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| 84 | </p><pre class="programlisting">
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| 85 | [ section name ] garbage \
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| 86 | param name = value
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| 87 | </pre><p>are read as</p><pre class="programlisting">
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| 88 | [section name]
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| 89 | param name = value
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| 90 | </pre></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id325754"></a>Syntax</h2></div></div></div><p>The syntax of the smb.conf file is as follows:</p><pre class="programlisting">
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| 91 | <file> :== { <section> } EOF
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| 92 | <section> :== <section header> { <parameter line> }
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| 93 | <section header> :== '[' NAME ']'
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| 94 | <parameter line> :== NAME '=' VALUE NL
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| 95 | </pre><p>Basically, this means that</p><div class="orderedlist"><ol type="1"><li><p>
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| 96 | a file is made up of zero or more sections, and is terminated by
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| 97 | an EOF (we knew that).
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| 98 | </p></li><li><p>
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| 99 | A section is made up of a section header followed by zero or more
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| 100 | parameter lines.
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| 101 | </p></li><li><p>
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| 102 | A section header is identified by an opening bracket and
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| 103 | terminated by the closing bracket. The enclosed NAME identifies
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| 104 | the section.
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| 105 | </p></li><li><p>
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| 106 | A parameter line is divided into a NAME and a VALUE. The *first*
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| 107 | equal sign on the line separates the NAME from the VALUE. The
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| 108 | VALUE is terminated by a newline character (NL = '\n').
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| 109 | </p></li></ol></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id325806"></a>About params.c</h3></div></div></div><p>
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| 110 | The parsing of the config file is a bit unusual if you are used to
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| 111 | lex, yacc, bison, etc. Both lexical analysis (scanning) and parsing
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| 112 | are performed by params.c. Values are loaded via callbacks to
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| 113 | loadparm.c.
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| 114 | </p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="vfs.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="pt03.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="wins.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 10. VFS Modules </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 12. Samba WINS Internals</td></tr></table></div></body></html>
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